SJ Gould on genome

Peter van Heusden pvh at egenetics.com
Fri Feb 23 02:00:09 PST 2001


On Thu, Feb 22, 2001 at 01:41:49PM -0500, Charles Brown wrote:
>
>
> >>> pvh at egenetics.com 02/21/01 04:34AM >>>
>
> Hm. There's a step missed out there - DNA to RNA.
>
> ((((((((
>
> CB: Aren't both DNA and RNA nucleic acids ( The "N" stands for "nucleic" and
> the "A" stands for "acid",no) ? Thus, the reference of transfer of info
> from nucleic acid to nucleic acid would include the step DNA to RNA .

I guess it could be...


>
> ((((((((
>
>
> And yes, well, that
> version of the Central Dogma has fallen prey to evidence years ago,
> with the discovery of retro-viruses (e.g. HIV), which splice their
> genetic material into DNA - i.e. information in the viral proteins
> quite literally gets into DNA.
>
> (((((((((
>
> CB: I thought viruses were bits of DNA or nucleic acid in protein cases.
> And that viruses put their DNA, nucleic acid , not protein, into the host
> cell. That would still be nucleic acid to nucleic acid.

Most viruses put their DNA or RNA into the host cell, and wait for the transcription/translation machinery to turn it into new viral proteins.

Retro-viruses put their nucleic acid into the host DNA - and the viral proteins do the job of putting it there. Those viral proteins seem to be pretty much violating the Central Dogma.
>
> If so,
> What is fallacy or weakness of practice in the following idea ?
>
>
> Shouldn't DNA sequencing make it a faster track to figuring out how to
> disarm incurable viruses ,such as HIV ? Sequence the DNA in the virus, and
> then synthesize a medicine that has a marker for the virus based on some
> unique sequence ;and that same medical molecule substitutes itself
> somewhere in the DNA of the virus and changes the sequences of the virus
> DNA so that the virus DNA cannot use the machinery of the host's cells to
> replicate the virus ???

This is exactly what some modern anti-viral treatments are aimed at. I can't recall the exact details right now, but one new treatment is aimed at degrading the protein used by HIV to grapple onto the cells it wants to infect. Sequencing viral DNA/RNA is important for research in these fields, although you need to then go on and model the 3D structure of viral proteins. Research in the lab I work at (SANBI) is focussing on examining where mutations in e.g. pathogens such as Plasmodium falciparum (the parasite responsible for malaria) occur - this should give us a handle on how the organism is responding to evade the host immune system / drugs. Mapping the sites of common mutation to a 3D model of the proteins produced gives you an idea of exactly what molecular mechanism for virulence is, which gives you a handle on how to make a better drug. (At which point the lab probably ends up selling this information to GlaxoSmithKline for megabucks, and the resulting drug is sold back to the South African health service for even more megabucks....)


>
> (((((((((
>
> CB: Uh huh. I'm wondering about the "regulatory networks". This sounds
> like a reference to a process that might involve info flow from proteins
> to DNA , violating the dogma as stated. As far as I can tell, it does
> not involve modifying the genes, but switching them on and off.

Nope, no modfication of genes, at least as far as I know. But, the CD is specifically talking about 'information' flow, so I think it is valid to argue that the conservation of information in "regulatory networks" is an argument against taking the CD literally.


>
> (((((((((((
>
> CB: Did any biologist ever argue that there were no environmental causes
> intervening between genotype and phenotype ? Isn't there something of a
> straw biologist being knocked down ?

Yes, I think it is a straw biologist - but unfortunately, the 'popular perception' of genetics resembles this straw biologist a bit, thanks largely to how science is reported in 'popular science' magazines and the general media. Peer review isn't perfect, but it does keep the stuff in Science and Nature at least a little bit less ridiculous than it could be - the most outrageous things are generally kept to the Letters page, or some journal like the Journal of Evolutionary Psychology (used to be the Journal of Socio-Biology). Things seems a bit better in biology than they are in economics, I think.

Peter -- Peter van Heusden <pvh at egenetics.com> NOTE: I do not speak for my employer, Electric Genetics "Criticism has torn up the imaginary flowers from the chain not so that man shall wear the unadorned, bleak chain but so that he will shake off the chain and pluck the living flower." - Karl Marx, 1844 OpenPGP: 1024D/0517502B : DE5B 6EAA 28AC 57F7 58EF 9295 6A26 6A92 0517 502B



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